Housing for disc-shaped semiconductor device



United States Patent 3,499,095 HOUSING FOR DISC-SHAPED SEMICONDUCTORDEVICE Joachim Hans, Ebermannstadt, Germany, assignor to SiemensAktiengesellschaft, a corporation of Germany Continuation-impart ofapplication Ser. No. 499,198, Oct. 21, 1965. This application Apr. 11,1968, Ser. No. 729,862 Claims priority, application Germany, Jan. 30,1965, S 95,262 Int. Cl. [105k 5/02 US. 'Cl. 174-52 8 Claims ABSTRACT OFTHE DISCLOSURE A housing structure for a disc-shaped semiconductordevice comprises a hollow cylindrical section of insulation material inwhich the semiconductor device is mounted. A first end member is affixedto one open end of the cylindrical section and closes it and a. secondend member is afiixed to the otheropen end of the cylindrical sectionand closes it. Each of the first and second end members comprises acentral portion and an outer portion of annular configuration having aninner rim afiixed to the central portion. Each central portion comprisesa metal of good thermal and electrical conductivity, such as copper orsilver, and each outer position has a thickness considerably less thanthat of the central portion as well as a fluted annular section formedin the outer portion at its inner rim.

DESCRIPTION OF THE INVENTION The present application is acontinuation-in-part application of my application Ser. No. 499,198,filed Oct. 21, 1965, now abandoned, for Housing for Disc-ShapedSemiconductor Device.

The present invention relates to a housing for a discshapedsemiconductor device. More particularly, the invention relates to a fiathousing structure for protecting a disc-shaped semiconductor device fromthermal stresses and the like.

A semiconductor rectifier or thyristor of disc shape such as, forexample, a silicon rectifier or a silicon thyristor may be enclosed in aflat housing. The housing is a hollow cylindrical section or ring ofinsulation material such as, for example, ceramic material, which isclosed at both its open or base ends with foil of a ductile metal havinggood current and heat conducting characteristics. The foil may comprisesilver, copper or the like, affixed to the cylindrical section at itsbases and covering the open ends thereof. The semiconductor device isheld in position between the foils and comprises a disc-shapedsemiconductor body of silicon, for example, and an aluminum foil alloyedwith the semiconductor body at one surface of the body. A metal carrierbody of molybdenum, for example, is joined with the aluminum foil andhas a thermal coefficient of expansion similar to that of thesemiconductor body. A large area electrode of a noble metal may bealloyed to the semiconductor body at the opposite surface of said body.If the semiconductor device is a thyristor, an additional or controlelectrode may be alloyed to the semiconductor body. A second molybdenumcarrier body having a suitable thermal coefiicient of expansion may bejoined to the large area electrode. The second carrier body is silverplated on its surface closer to the semiconductor body and has a recessformed therein to insulate the control electrode therefrom, if a controlelectrode is utilized. The noble metal surfaces of the semiconductor andcarrier bodies are tightly joined by the application of heat at suitableice temperatures. The semiconductor device may be positioned in a frametightly enclosed in the housing.

Large semiconductor devices are housed under pressure between largecooling bodies, which may be cooled by liquid or suitable cooling fluid,in order to dissipate the heat resulting from operation of such devices.Since the cooling bodies contact the metal foils at substantially planarsurfaces, the cylindrical section is substantially freely movable. Thus,an outside force component, in the direction of the axis of thecylindrical section, which has a sutficiently large magnitude, wouldtear the metal foils in their rim areas. Rather complicated supportingand centering devices are thus required for the semiconductor device. Ina large semiconductor device the forces and pressures on the metal foilsare greater than in small devices. These forces and pressures resultfrom temperature changes which occur during operation and are due to thevarious different thermal coetficients of expansion. The temperaturechanges occurring during operation produce stresses in the solderconnections of the silver foils with the ceramic ring as well as in thesilver foils themselves.

The principal object of the present invention is to provide a new andimproved housing structure for a discshaped semiconductor device.

An object of the present invention is to provide a housing structure forprotecting a disc-shaped semiconductor device from damage due toexternal forces.

In accordance with the present invention, a housing structure for adisc-shaped semiconductor device comprises a substantially cylindricalsection of insulation material which is hollow and which has spacedopposite open end bases. A first end member is afiixed to one open endbase of the cylindrical section and closes the one open end thereof. Thefirst end member comprises a first central portion of substantiallythick disc configuration and a first outer portion of substantiallyannular configuration having an inner rim affixed to the first centralportion. The first central portion comprises copper or silver. The firstouter portion comprises an iron-cobaltnickel alloy and has a thicknessconsiderably less than the thickness of the first central portion. Afluted annular section is formed in the first outer portion at its innerrim. A second end member is affixed to the other open end base of thecylindrical section and closes the other open end thereof. The secondend member comprises a second central portion of substantially thickdisc configuration and a second outer portion of substantially annu--lar configuration having an inner rim affixed to the second centralportion. The second central portion comprises copper or silver. Thesecond outer portion comprises an iron-cobalt-nickel alloy and has athickness consider-ably less than the thickness of the second centralportion. A fluted annular section is formed in the second outer portionat its inner rim. A disc-shaped semiconductor device is mounted in thecylindrical section between the first and second end. members.

Each of the first and second outer portions may comprise one of themetals nickel, copper or silver.

In an illustrated embodiment of the present invention, each of the firstand second central portions has good electrical and heat conductingcharacteristics and each of the first and second outer portions has athermal coefficient of expansion similar to that of the cylindricalsection. Each of the first and second central portions has a firstprincipal surface substantially adjacent the semiconductor device', asecond principal surface spaced from and substantially parallel to thefirst principal surface, a substantially annular mid-surface, asubstantially cylindrical step surface substantially perpendicular toand joining the first and mid-surfaces and a substantially cylindricalouter peripheral surface substantially perpendicular to and joining thesecond and mid-surfaces.

In the illustrated embodiment of the present invention, an annulargroove is formed in the mid-surface of each of the first and secondcentral portions. The inner rim of the fluted annular section of thefirst outer portion is fastened in the annular groove formed in themid-surface of the first central portion and the inner rim of the flutedannular section of the second outer portion is fastened in the annulargroove formed in the midsurface of the s cond central portion.

In order that the present invention may be readily carried into effect,it will now be described with reference to the accompanying drawing,wherein:

FIG. 1 is a sectional view of an embodiment of the housing structure ofthe present invention housing a discshaped semiconductor rectifier;

FIG. 2 is a sectional "view of a modification of the embodiment of FIG.1 housing a disc-shaped semiconductor thyristor; and

FIG. 3 is a view of a housing structure of the present invention in aclamping device between two cooling bodies.

A silicon semiconductor body 2 of disc shape is assumed to have adiameter of 3.0 cm. and the diameters of the other components of thesemiconductor device and of the housing structure are illustrated insubstantially their proportion to said semiconductor body. Thethicknesses of some of the components are greatly exaggerated in orderto maintain the clarity of illustration.

The housing structure of FIG. 1 comprises a hollow cylinder 8 ofinsulation material such as, for example, ceramic material. An endmember is affixed to the lower open end or base surface of the cylinderor ring 8 and an identical end member is afiixed to the upper open endor base surface of the cylinder or ring 8. The end members are coaxiallypositioned with the cylinder 8 and each of said end members comprises acentral portion 12 of substantially thick disc configuration and anouter portion 10 of substantially annular configuration.

The central portion 12 of each of said end members comprises goodelectrical and heat conducting material such as, for example, copper,silver, or the like, and the outer portion 10 of each of said endmembers is of a material having a thermal coeflicient of expansionsimilar to that of the ceramic material such as, for example, nickel,copper, silver, or an iron-cobalt-nickel alloy. The upper end member andits components and parts are identified by the same reference numeralsas the lower end member and its components and parts, primed.

A semiconductor device 1 of disc shape is positioned between the endmembers 12, 10' and 12, 10' and comprises a silicon disc orsemiconductor body 2 having a diameter of approximately 3.0 cm. and athickness of approximately 300 microns. An aluminum electrode (notshown) is alloyed to the lower surface of the semiconductor body 2 and afirst disc-shaped carrier body or plate 3 is afiixed to the aluminumelectrode by heating. The first carrier body 3 comprises molybdenum,tungsten, or the like. A gold-antimony electrode (not shown) is alloyedto the upper surface of the semiconductor body 2. A silver foil 6 ispositioned on the upper surface of the goldantimony electrode and asecond disc-shaped carrier body or plate 4 is positioned on the uppersurface of the silver foil 6. The second carrier body 4 comprisesmolybdenum, tungsten, or the like. The lower surface of the secondcarrier plate 4 may be plated with the silver foil 6 and said carrierplate may then be affixed to the gold-antimony electrode by heating.Either or both of the first and second carrier bodies may be silverplated.

The semiconductor device 1 is positioned between the central portions 12and 12' of the end members. The upper central portion 12' is stepped orgradated down in a down step which is substantially perpendicular to theprincipal surface areas thereof, said down step being substanti y pa ael. in c oss section with d coax y n concentrically positioned with theouter peripheral surface of said central portion. The central portion12' thus comprises a substantially planar, substantially circular uppersurface, a substantially planar, substantially circular lower surface, asubstantially planar annular lower mid-surface, a substantiallycylindrical step surface perpendicular to and joining the lower andlower mid-surfaces, and a substantially cylindrical outer peripheralsurface perpendicular to and joining the lower midand upper surfaces.

The upper and lower central portions 12' and 12, respectively, of theupper and lower end members are stepped or graduated toward each other.Thus, the lower central portion 12 is stepped or gradated up in an upstep which is substantially perpendicular to the principal surface areasthereof, said up step being substantially parallel in cross section withand coaxially and concentrically positioned with the outer peripheralsurface of said central portion. The central portion 12 thus comprises asubstantially planar, substantially circular lower surface, asubstantially planar, substantially circular upper surface, asubstantially planar annular upper mid-surface, a substantiallycylindrical step surface perpendicular to and joining the upper andupper mid-surfaces, a substantially cylindrical outer peripheral surfaceperpendicular to and joining the upper midand upper surfaces.

An annular groove or channel 15' is formed in the lower mid-surface ofthe upper central portion 12 and has solder therein. An annular grooveor channel 15 is formed in the upper mid-surface of the lower centralportion 12 and has solder therein. A substantially annular member orwasher 10' is coaxially afiixed to the upper central portion 12' byhaving a portion thereof inserted into the channel 15 and hard solderedtherein. A substantially annular member or washer 10 is coaxiallyaflixed to the lower central portion 12 by having a portion thereofinserted into the channel 15 and hard soldered therein. Each of theannular members 10 and 10' comprises a material having a thermalcoefficient of expansion corresponding to that of the ceramic ring 8such as, for example, an iron-cobalt-nickel alloy.

The upper anl lower central portions 12' and 12 may each have athickness, in the direction of the axis, of, for example, 8 mm. betweenthe upper and lower surfaces, whereas the upper and lower annularmembers 10' and 10 may each have a thickness, in the direction of theaxis, of, for example, 0.5 mm. The upper and lower annular members 10"and 10 are substantially identical. A fluted annular section, channel orgroove 21 is formed in the upper annular member 10 at its inner rim,opening upward. A fluted annular section, channel or groove 21 is formedin the lower annular member '10 at its inner rim, opening downward. Theinnermost rim of each of the upper and lower annular members, which isthe cylindrical inner portion of each of said members and of the annularchannel 21' and 21, respectively, thereof, is inserted into thecorresponding annular channel 15 and 15, respectively, of the upper andlower central portions 12' and 12, respectively, and hard solderedtherein. These solder connections are only slightly stressed by radiallydirected forces.

An upper annular member or washer 9' of substantially L-shapedcross-sectional area is afiixed by suitable means such as hard solder tothe upper portion of the outer cylindrical surface of the ceramic ring 8and to the lower outside rim area surface of the upper annular member10' by suitable means such as welding. The inner cylindrical surface ofthe washer 9' is affixed to the upper portion of the outer cylindricalsurface of the ceramic ring 8 in a manner whereby the upper surface ofthe substantially perpendicular part of said washer 9' is spaced abovethe upper open end or base of said ceramic ring, so that the upperannular member 10' supported by said perpendicular part at its uppersurface, is spaced from said ceramic ring.

A lower annular member or washer 9 of substantially L-shapedcross-sectional area is affixed by suitable means such as hard solder tothe lower portion of the outer cylindrical surface of the ceramic ring 8and to the upper outside rim area surface of the lower annular member bysuitable means such as welding. The inner cylindrical surface of thewasher 9 is aflixed to the lower portion of the outer cylindricalsurface of the ceramic ring 8 in a manner whereby the lower surface ofthe substantially perpendicular part of said washer 9 is spaced belowthe lower open end or base of said ceramic ring, so that the lowerannular member 10, supported by said perpendicular part at its lowersurface, is spaced from said ceramic ring.

Each of the upper and lower washers 9' and 9 comprises aniron-cobalt-nickel alloy and each has a thickness, in the direction ofthe axis, of 0.5 mm. The innermost rim of each of the upper and lowerannular members, which is inserted into the corresponding annularchannel of the respective upper and lower central portions, is extendingbeyond the plane of the principal annular surface area of said upper andlower annular member in a manner whereby said upper and lower centralportions are so positioned that their outer surfaces extend beyond theprincipal annular surface areas of said upper and lower annular members.Thus, the innermost rim of the upper annular member 10' extends upwardbeyond the plane of the principal annular surface area of said upperannular member in a manner whereby the upper central portion 12'supported thereby is positioned with its upper surface extending fartherfrom the semiconductor device than said principal annular surface areaof said upper annular member. The innermost rim of the lower annularmember 10 extends downward beyond the plane of the principal annularsurface area of said lower annular member in a manner whereby the lowercentral portion 12 supported thereby is positioned with its lowersurface extending farther from the semiconductor device than saidprincipal annular surface area of said lower annular member.

Each of the annular members 10 and 10' is flexible under stress due tothe channel 21 and 2-1, respectively, formed therein. The annularmembers 10 and 10' thus yield under stress or forces such as, forexample, are caused by temperature changes during operation or outsideinfluences acting on the insulator ring 8 in radial directions.

A silver foil 5, which is approximately .02 mm. thick, is preferablyprovided between the carrier body 4 and the upper central portion 12'and a similar silver foil 7 is preferably provided between the carrierbody 3 and the lower central portion 12. The silver foils provide abalance for thermal expansion of the upper and lower central portionsand the corresponding carrier bodies, due to the slidable pressurecontact thus provided between said central portions and saidcorresponding carrier bodies. The corresponding surfaces of the carrierbodies may be plated with silver or silver foil.

The semiconductor device 1 may be centered in axial position in thehousing structure by centering pins 14 and 14 positioned in bores 13 and13 formed in the upper surface of the lower central portion 12 and thelower surface of the upper central portion 12', respectively. The pinsextending from each central portion 12 and 12' may be positioned, forexample, at the apices of an equilateral triangle. The pins 14 and 14may be fastened in the corresponding bores 13 and '13, respectively, byany suitable means. An evacuation nipple (not shown) may be aflixed toone of the annular members 10 and 10' by suitable means such as hardsolder.

The semiconductor device 1 may be positioned in the housing structure byfirst hard soldering the annular members 9 and 9 to the ceramic ring 8in the aforedescribed manner and relation. The annular members 10 and10' are then hard soldered to the central portions 12 and 12' in theaforedescribed manner and relation via the soldercontaining channels 15and 15, respectively. The central portions 12 and 12' usually have alarger thermal coefficient of expansion than the annular members 10 and10 so that the radial width of the channel 15 and of the channel 15' isgreater than the thickness of the innermost rim of each of the annularmembers 10 and 10 which is soldered into such channel. The radial widthof the channel is approximately twice the thickness of the innermostrim.

In affixing the central portions to the annular members, it ispreferable to position such components so that the innermost rim of theannular member is adjacent the outermost cylindrical surface of thegroove in the central portion into which the innermost rim of theannular member is inserted. This assures sufiicient room for movement ofthe annular members 10 and 10' in the channels 15 and 15, respectively,when the central portions 12 and 12 expand during the soldering process.

After the annular members 10 and 10' are soldered to the centralportions 12 and 12, respectively, the lower surface of the upper centralportion 12' and the upper surface of the lower central portion 12 arelapped and, if centering pins 14 are to be utilized, bores are providedin such surfaces for such pins. The semiconductor device 1 and thesilver foils 5 and 7 are positioned between the central portions 12 and12' in centered position and the annular members 10 and 10' are weldedto the annular members 9 and 9, respectively.

FIG. 2 shows part of a modification of the embodiment of FIG. 1 which isfor housing a thyristor. The same components of FIGS. 1 and 2 areidentified by the same reference numerals. In the modification of FIG.2, the upper annular member 10' of FIG. 1 is replaced by an upperannular member 11. The annular member 11 is similar to the annularmember 10 except that the radial width of the fluted annular section,groove or channel 22 formed therein at its inner rim is greater than theradial width of the fluted annular section, groove or channel 21 of theannular member 10. The innermost rim of the upper annular member 11 isthus of cylindrical configuration having a smaller diameter than theinnermost rim of the lower annular member 10. Thus, the step rimdiameter and the outer rim diameter of the upper central portion 12' aregreater than the corresponding diameters of the lower central portion12.

A substantially cylindrical body of insulating material 17 such as, forexample, ceramic material, passes through an aperture formed through theannular member 11 in the groove 22 and may be affixed thereto by hardsolder. A central bore is provided through the cylindrical body 17 andan electrically conductive pin 19 is positioned in said bore with itslower part in the space between the central portions 12 and 12 and witha disc-type head aflixed to its upper part and resting on the uppersurface of the cylindrical body. The pin head may be hard soldered tothe cylindrical insulator 17 and the pin may comprise aniron-cobalt-nickel alloy. An electrical conductor 20 is electricallyconnected to the pin 19 at its upper part and is held in position by aclamp 18 affixed to the upper surface of the upper annular member 11 bysuitable means such as hard solder. The pin 19 electrically contacts thecontrol electrode of a thyristor (not shown) positioned in the housingof FIG. 2. A silver connector (not shown) may be utilized toelectrically connect the pin 19 and the control electrode of thethyristor.

The semiconductor device 1 may be positioned in a frame (not shown) andtightly enclosed in the housing, a suitable frame being disclosed incopending patent application Ser. No. 482,460, filed Aug. 25, 1965, andassigned to the assignee of the present invention. Such a frame fitssnugly within the inside cylindrical surface of the insulator ring 8.Any suitable positioning arrangement may be utilized to maintain theframe in position.

The semiconductor device 1 may be positioned in the housing structure ofFIG. 2 by first positioning said semiconductor device in a frame, if aframe is to be utilized. The annu ar members 9, 9 and 10 and 11 are thenhard soldered in the same manner as in the embodiment of FIG. 1 to theappropriate components. The lower surface of the upper central portion12 and the upper surface of the lower central portion 12 are lapped. Thesemiconductor device 1, in the frame, if such is utilized, is thenpositioned on the upper central portion 12 and any positioningarrangement for the frame is engaged. The pin 19 is placed in contactwith the control electrode of the thyristor semiconductor device 1. Theceramic ring-8 is then positioned on and around the frame and the lowercentral portion 12 is affixed by hard solder to the lower annular member10. The annular members 11 and 10 are then welded to the upper and lowerannular members 9' and 9, respectively.

FIG. 3 shows a housing structure of the present invention in a clampingdevice. In FIG. 3, the semiconductor device 30 is positioned between twocooling bodies 31 and 31. Each of the cooling bodies 31 and 31' maycomprise, for example, copper. Each of the cooling bodies 31 and 31 hasinlet and outlet ducts for cooling fluid and electrical terminals. Thus,the upper cooing body 31' has inlet and outlet ducts 32 for coolingfluid, and electrical terminals (not shown), and the lower cooling body31 has inlet and outlet ducts 32 for cooling fluid, and electricalterminals (not shown).

The clamping device comprises a base plate 33, an upper plate 23 andconnecting members 34 between said base plate and said upper plate, allcomprising steel. A tightening bolt or threaded member 36 is threadedlyengaged and positioned in an aperture formed through the upper plate 23and abuts at its lower end against a clamping disc 37 which iselectrically insulated and is positioned on the upper surface of theupper cooling body 31'. A centering ring 38 may be aflixed to the lowersurface of the upper cooling body 31', and a centering ring 38 may beaffixed to the upper surface of the lower cooling body 31 for centeringthe semiconductor device 30 in position. A centering ring 39 may beafirxed to the upper surface of the base plate 33 for centering thelower cooling body 31.

While the invention has been described by means of specific examples andin specific embodiments, I do not wish to be limited thereto, forobvious modifications will occur to those skilled in the art withoutdeparting from the spirit and scope of the invention.

I claim:

1. A housing structure for a disc-shaped semiconductor device having acontrol electrode, comprising a substantially cylindrical section ofinsulation material, said cylindrical section being hollow and havingspaced opposite open end bases;

a first end member afiixed to one open end base of said cylindricalsection and closing the one open end thereof, said first end membercomprising a first central portion of substantially thick discconfiguration and a first outer portion of substantially annularconfiguration having an inner rim aflixed to said first central portion,said first central portion comprising a metal of good thermal andelectrical conductivity and said first outer portion having a thicknessconsiderably less than the thickness of said first central portion, anda fluted annular section formed in said first outer portion at its innerrim;

a second end member aifixed to the other open end base of saidcylindrical section and closing the other open end thereof, said secondend member comprising a second central portion of substantially thickdisc configuration and a second outer portion of substantially annularconfiguration having an inner rim affixed to said second centralportion, said second central portion comprising a metal of good thermaland electrical conductivity and said second outer portion having athickness considerably less than the thickness of said second centralportion,

. and a fluted annular section formed in said second outer portion atits inner rim;

insulating means mounted on one of said first and second outer portions,said insulating means having a bore formed therethrough into saidhousing structure, electrical conducting means inserted in said bore andconnected to said control electrode, electrical conducting means outsidesaid housing and connecting means connecting said electrical conductingmeans to each other; and

mounting means mounting a disc-shaped semiconductor device in saidcylindrical section between said first and second end members.

2. A housing structure for a disc-shaped semiconductor device,comprising a substantially cylindrical section of insulation material,said cylindrical section being hollow and having spaced opposite openend bases;

a first end member aflixed to one open end base of said cylindricalsection and closing the one open end thereof, said first end membercomprising a first central portion of substantially thick discconfiguration and a first outer portion of substantially annularconfiguration having an inner rim affixed to said first central portion,said first central portion comprising a metal of good thermal andelectrical conductivity and said first outer portion having a thicknessconsiderably less than the thickness of said first central portion, anda fluted annular section formed in said first outer portion at its innerrim;

a second end member affixed to the other open end base of saidcylindrical section and closing the other open end thereof, said secondend member comprising a second central portion of substantially thickdisc configuration and a second outer portion of substantially annularconfiguration having an inner rim aflixed to said second centralportion, said second central portion comprising a metal of good thermaland electrical conductivity and said second outer portion having athickness considerably less than the thickness of said second centralportion, and a fluted annular section formed in said second outerportion at its inner rim, each of said first and second central portionshaving a first principal surface substantially adjacent saidsemiconductor device, a second principal surface spaced from andsubstantially parallel to said first principal surface, a substantiallyannular mid-surface, a substantially cylindrical step surfacesubstantially perpendicular to and joining said first and mid-surfacesand a substantially cylindrical outer peripheral surface substantiallyperpendicular to and joining said second and mid-surfaces, an annulargroove formed in the mid-surface of each of said first and secondcentral portions, fastening means for fastening the inner rim of thefluted annular section of said first outer portion in the annular grooveformed in the mid-surface of said first central portion and fasteningmeans for fastening the inner rim of the fluted annular section of saidsecond outer portion in the annular groove formed in the mid-surface ofsaid second central portion; and

mounting means mounting a disc-shaped semiconductor device in saidcylindrical section between said first and second end members.

3. A housing structure as claimed in claim 2, further comprisingpositioning pins extending from the first principal surface of each ofsaid first and second central portions centrally positioning saidsemiconductor device.

4. A housing structure as claimed in claim 2, further comprising firstlinking means afiixed to the other cylindrical surface of saidcylindrical section for supporting said first end member in spacedrelation to said one open.

end base of said cylindrical section and second linking means aflixed tothe outer cylindrical surface of said cylindrical section for supportingsaid second end member in spaced relation to said other open end base ofsaid cylindrical section.

5. A housing structure as claimed in claim 4, wherein each of said firstand second linking means is of substantially L-shaped cross-sectionalarea and comprises a material having a thermal coefiicient of expansionsimilar to that of said cylindrical section.

6. A housing structure as claimed in claim 5, wherein said first outerportion of said first end member is aifixed to said first linking meansand said second outer portion of said second end member is afiixed tosaid second linking means.

7. A housing structure for a disc-shaped semiconductor device,comprising a substantially cylindrical section of insulation material,said cylindrical section being hollow and having spaced opposite openend bases;

a first end member affixed to one open end base of said cylindricalsection and closing the one open end thereof, said first end membercomprising a first central portion of substantially thick discconfiguration and a first outer portion of substantially annularconfiguration having an inner rim afiixed to said first central portion,said first central portion comprising one of the metals copper or silverand said first outer portion comprising an iron-cobalt-nickel alloy andhaving a thickness considerably less than the thickness of said firstcentral portion, and a fluted annular section formed in said first outerportion at its inner nm;

a second end member afiixed to the other open end base of saidcylindrical section and closing the other open end thereof, said secondend member comprising a second central portion of substantially thickdisc configuration and a second outer portion of substantially annularconfiguration having an inner rim afiixed to said second centralportion, said second central portion comprising one of the metals copperor silver and said second outer portion comprising an ironcobalt-nickelalloy and having a thickness considerably less than the thickness ofsaid second central portion, and a fluted annular section formed in saidsecond outer portion at its inner rim;

mounting means mounting a disc-shaped semiconductor device in saidcylindrical section between said first and second end members;

a molybdenum carrier plate positioned on one side of said semiconductordevice; and

10 silver foil positioned between said carrier plate and thecorresponding one of said first and second central portions.

8. A housing structure for a disc-shaped semiconductor device,comprising a substantially cylindrical section of insulation material,said cylindrical section being hollow and having spaced opposite openend bases;

a first end member affixed to one open end base of said cylindricalsection and closing the one open end thereof, said first end membercomprising a first central portion of substantially thick discconfiguration and a first outer portion of substantially annularconfiguration having an inner rim affixed to said first central portion,said first central portion comprising one of the metals copper or silverand said first outer portion comprising an iron-cobalt-nickel alloy andhaving a thickness considerably less than the thickness of said firstcentral portion, and a fluted annular section formed in said first outerportion at its inner rim, at least one of said first and second centralportions being silver plated;

a second end member afiixed to the other open end base of saidcylindrical section and closing the other open end thereof, said secondend member comprising a second central portion of substantially thickdisc configuration and a second outer portion of substantially annularconfiguration having an inner rim afiixed to said second centralportion, said second central portion comprising one of the metals copperor silver and said second outer portion comprising an iron-cobalt-nickelalloy and having a thickness considerably less than the thickness ofsaid second central portion, and a fluted annular section formed in saidsecond outer portion at its inner rim; and

mounting means mounting a disc-shaped semiconductor device in saidcylindrical section between said first and second end members.

References Cited UNITED STATES PATENTS 2,066,856 1/1937 Rose.

3,23 8,425 1/1966 Geyer. 3,280,389 10/1966 Martin. 3,310,716 3/1967Emeis.

LEWIS H. MYERS, Primary Examiner D. A. TONE, Assistant Examiner U.S, Cl.X.R. 3 17234

